N.V. Costa

Características morfológicas de gramas em resposta à aplicação de trinexapac-ethyl

The aim of this research was to evaluate the effects of the sequential application of two rates of trinexapac-ethyl on the morphology of the following turf grass species: Broadleaf Carpetgrass (Axonopus compressus), Bahiagrass (Paspalum notatum), St. Augustinegrass (Stenotaphrum secundatum) and Korean Lawngrass (Zoysia japonica). The treatments used were trinexapac-ethyl with two sprays applied at 20 day interval at two different rates (56.5 + 56.5 and 113.0 + 113.0 g ha-1) and a control without spraying, for each species. The turf grasses were cut at the height of 3 cm, and sprayed after the treatments. Twenty days after the first treatment application, the plots were cut again and the second treatment application was carried out. The experiment was arranged in a completely randomized block design with four replications. Growth reduction was evaluated based on the height of the plants. Inflorescence number and height were weekly evaluated by sampling, carried out in 0.25 m2 in the center of the plots. Total dry matter was evaluated at the end of the experiment. Ttrinexapac-ethyl application delayed growth and inflorescence emission and did not cause any visual damage to the turf grasses. Trinexapac-ethyl application can reduce the need of cuts for a period up to 55 days after the second application.

Ecophysiology of seed germination in Digitaria insularis ((L.) Fedde)

The invasive behaviour of sourgrass (Digitaria insularis) in cultivated areas is due to its strategy of aggressive regeneration, which is based on seed germination. Knowledge of the physiological ecology of this species can contribute to the development of management and control strategies. The aim of this research was to understand the effects of provenance, temperature and light on the germination of sourgrass seeds collected in the Brazilian state of Sao Paulo in the cities of Americana, Botucatu and Sao Jose do Rio Preto and in the state of Parana in the city of Sao Miguel do Iguacu. The seeds were left to germinate at temperatures of 15, 25, 35 and 45 °C, both with and without light. The number of normal seedlings was recorded daily from seven to 60 days. After this period, the seeds together with substrate, were transferred to 25 oC with light, and a daily count was made for all treatments until the end of germination (75 days after sowing). The seeds of D. insularis are positively photoblastic. Seed germination in this species depends on provenance. A temperature of 4 5 °C for germination is lethal to the seeds. The temperature of 35 °C in the presence of light is the most favourable condition for seed germination.

Seletividade e eficiência de herbicidas aplicados em pré-emergência na cultura da mandioca

The chemical control of weeds stands out as an important tool for obtaining high yields in cassava crops. This study aimed at evaluating the selectivity and efficiency of pre-emergent herbicides on cassava (‘Cascuda’ cultivar) crop. The experimental design was randomized blocks, with ten treatments and four replications. The treatments consisted of clomazone (900 g ha -1 and 1,080 g ha -1 ), flumioxazin (60 g ha -1 ), sulfentrazone (600 g ha -1 ), S-metolachlor (1,920 g ha -1 ), clomazone + flumioxazin (900 + 50 g ha -1 ), clomazone + sulfentrazone (900 + 500 g ha -1 ) and clomazone + S-metolachlor (900 + 1,440 g ha -1 ), as well as a weeded and a non-weeded control. The weed community was composed by 9 families and 12 species, with the Asteraceae and Poaceae families presenting the highest number of species. The pre-emergent herbicides were selective for ‘Cascuda’ cultivar cassava plants. The herbicides were effective in controlling weeds, with flumioxazin (60 g ha -1 ), sulfentrazone (600 g ha -1 ), S-metolachlor (1,920 g ha -1 ) and the mixtures of clomazone + flumioxazin (900 + 50 g ha -1 ), clomazone + sulfentrazone (900 + 500 g ha -1 ) and clomazone + S-metolachlor (900 + 1,440 g ha -1 ) presenting the highest residual effect.

Effect of plant regulators on growth and flowering of 'Meyer' zoysiagrass

Este trabalho teve o proposito de avaliar o efeito da aplicacao sequencial de diferentes reguladores vegetais sobre o crescimento e a emissao de hastes florais da grama-esmeralda (Zoysia japonica). O estudo foi instalado em um gramado com 15 meses, no delineamento de blocos casualizados com quatro repeticoes, e os reguladores de crescimento e doses testados foram: trinexapac-ethyl (113+113, 226+113, 226+226, 452+113, 452+226, 452+452, 678+339 e 904+452 g i.a. ha-1), prohexadione-calcium (100+100 e 200+200 g i.a. ha-1) e bispyribac-sodium (40+40 e 60+60 g i.a. ha-1), alem de uma testemunha sem aplicacao de regulador de crescimento. Quando os tratamentos atingiram altura entre 5,0 e 6,0 cm, o gramado foi novamente aparado a 3,0 cm de altura, sendo em seguida realizada a aplicacao da segunda dose dos reguladores. O efeito dos tratamentos foi avaliado quanto a fitointoxicacao, por meio de avaliacao visual, altura de plantas, altura e emissao de hastes florais e producao de massa seca de aparas. Apenas o bispyribac-sodium apresentou sintomas visuais de injuria, nao se verificando mais intoxicacao aos 28 dias apos a segunda aplicacao (DAAB). As aplicacoes sequenciais do trinexapac-ethyl, prohexadione-calcium e bispyribac-sodium apresentaram reducoes acima de 80% na quantidade total de massa seca de aparas produzidas pela grama-esmeralda. Todos os reguladores de crescimento tambem demonstraram ser promissores em relacao ao retardamento do crescimento e da emissao das inflorescencias, com especial destaque para o trinexapac-ethyl aplicado nas doses de 452+452, 678+339 e 904+452 g i.a. ha-1. Gramados formados com grama-esmeralda podem ser manejados com a aplicacao sequencial de regulador vegetal, com a reducao da necessidade de cortes por um periodo de ate 110 dias apos a aplicacao, alem de nao causar efeito deleterio no aspecto visual sobre o gramado.

Determinação dos períodos de interferência de plantas daninhas na cultura do girassol

The aim of this study was to determine the period prior to interference and the total period of prevention against interference of weeds in sunflower (hybrid M 734). The experiment was arranged in a complete randomized block design, with four replications. The treatments consisted of plots constituted by periods of control and presence of weeds. For the control periods, the sunflower plants were kept wedd free during increasing periods of 7, 14, 21, 28, 35, 42, 49 and 125 days after emergence (DAE). During cohabitation, the sunflower culture was maintained in the presence of the weed community during the same periods. Total density and dry weight of the weeds and plant height, chapter diameter, seed yield and oil of the sunflower plants were evaluated. For seed yield, the period before interference was 15 DAE of the culture, and the total period of prevention against weed interference was 39 DAE. The critical period of weed interference covered 24 days of the sunflower cycle. As for oil yield, the period before interference was 32 DAE, while the total period of prevention against weed interference was 28 DAE.

Levantamento de plantas aquáticas no reservatório de Salto Grande, Americana-SP

The objectives of this work were to determine the relative frequency and infestation level of each species present in the Salto Grande Reservoir in Americana-SP. The survey and identification of the aquatic plants were carried out in the Salto Grande reservoir on a boat. Twenty evaluation sites were established along the reservoir, photographed and geo-referenced. Values from 0 to 100% were assigned for both the species present and for the aquatic plants that could possibly occur within the sampled sites. Based on the number of individuals and points evaluated, the relative frequency of each species was determined. Thirteen species were identified along the reservoir, 12 vascular species and one green alga (Chlorella spp.). Among the vascular species , nine were floating plants, anchored or not on the bed of the reservoir, namely, Alternanthera philoxeroides, Brachiaria subquadripara, Cyperus difformis, Echinochloa polystachia var. spectabilis, Eichhornia crassipes, Panicum rivulare, Pistia stratiotes, Salvinia auriculata and Typha angustifolia. Other three species were found only on firm ground, namely, Aeschynomene sensory, Hedychium coronarium and Mimosa pigra.

Uniformidade de deposição de gotas de pulverização em plantas de amendoim e Brachiaria plantaginea

The objective of this study was to evaluate the uniformity of spray deposition on peanut and on the weed Brachiaria plantaginea in crop rows and inter-rows. The study was conducted in the field with the peanut cultivar IAC Tatu-ST, and the applications were carried out at the vegetative (V1) and reproductive (R2) stages of the culture. Brilliant Blue (FDC only the spray nozzle XR 11002 VS (200 L ha-1) showed no deposition failures at both stages of development of B. plantaginea located on the crop line. As for the plants located between the rows, the spray nozzles were most efficient at the 3-5 tiller stage.

Seletividade de herbicidas aplicados em pré-emergência em gramíneas forrageiras

This study aimed to evaluate the selectivity of pre-emergence herbicides on yield and seed quality of Brachiaria brizantha cv. Brizantha and Brachiaria decumbens cv. Basilisk. The herbicides evaluated were: diuron (800 and 1.600 g ha-1), ametryn (625 and 1.250 g ha-1), imazaquin (75 and 150 g ha-1), imazethapyr (50 and 100 g ha-1) and flumetsulam (70 and 140 g ha-1), plus a control without herbicide application. The species were evaluated separately in the field. The experiments were arranged in a randomized block design with four replications. The herbicides ametryn (625 g ha-1), imazaquin (75 and 150 g ha-1), imazethapyr (50 and 100 g ha-1), and flumetsulam (70 and 140 g ha-1) provided the highest selectivity to B. brizantha plants, while for B. decumbens, diuron (800 and 1.600 g ha-1), ametryn (625 and 1.250 g ha-1), and imazethapyr (50 and 100 g ha-1) were more selective, especially diuron, at the lowest dose. However, the tested herbicides do not affect the yield and quality of the seeds of the forage grasses studied.

Alterações anatômicas foliares em Eichhornia crassipes submetidas à aplicação de herbicidas

The aim of this work was to evaluate the efficacy of 2,4-D, diquat and glyphosate control and the leaf blade anatomic changes provided by these herbicides in Eichhornia crassipes, collected in the reservoirs of the CESP complex. The plants were grown in reservoirs containing water under field conditions. When these plants reached the stage of full vegetative development, they were sprayed with solutions of diquat at 400 g a.i. ha-1 , 2,4-D at 1.340 g a.e. ha-1 and glyphosate at 4.320 g a.e. ha 1 in combination with Silwet L-77 at 0.01% v v-1.A control without herbicide was also used .Evaluations were carried out of the control and of the following anatomical quantitative characteristics of the vein and intervein central regions of the leaf blade: percentage of the adaxial and abaxial epidermis, percentage of the endoderm, percentage of vascular bundle, percentage of the aerenchyma lacuna, percentage of parenchyma and leaf thickness (µm). According to the results, the main anatomical quantitative characters of the vein and intervein central regions of the leaf blade that changed after herbicide application were: percentage of the adaxial epidermis, percentage of the endoderm, and leaf thickness. Diquat and 2,4-D promoted changes in the anatomical quantitative characters of the vein and intervein central regions of the leaf blade in E. crassipes. Only glyphosate provided 100% of E. crassipes control at 22 days after application, compared with the control without herbicide.

Avaliação de pontas de jato plano na deposição da calda de pulverização com diferentes combinações de plantas de feijão, Brachiaria plantaginea e Bidens pilosa

The objective of this study was to evaluate flat fan nozzle spray deposition on different combinations of the common bean plants, Brachiaria plantaginea and Bidens pilosa, in two volumes of application, with and without the addition of surfactant. Brilliant blue FDC -1 was used as tracer solution at the concentration of 500 ppm to evaluate the deposition. The treatments consisted of 7 combinations of plants: (common bean); (B. plantaginea); (B. pilosa); (common bean + B. plantaginea); (common bean + B. pilosa); (B. plantaginea + B. pilosa) and (common bean + B. plantaginea + B. pilosa). The experiment was arranged in a randomized block design. The flat fan nozzles XR 110015 VS and XR 11002 VS were evaluated, with volumes of application of 150 and 200 L ha-1 , respectively, with and without the surfactant Silwet at 0.05% v v-1. After application, the plants were immediately collected and washed in 100 mL of distilled water for posterior tracer quantification in the spectrophotometer. The flat fan nozzles presented distinct behavior in droplet deposition on the species studied; the addition of a surfactant to the spray solution increased deposition uniformity, and contributed to the reduction of the volume application.